Thermo Scientific 42iQHL Instruction Manual page 115

Operation
Settings
When the low range is active, the range mode selection status output is
at 0 volts. When the high range is active, the range mode selection
status output is at half of full-scale.
When the high range is active, the NO concentration must drop to
x
95% of the low NO range for the low range to become active.
x
In addition to each channel having two ranges, each channel has two
span coefficients. There are two span coefficients so that each range can
be calibrated separately. This is especially necessary if the two ranges are
not close to one another. For example, the low NO range is set to 0–50
ppm and the high NO range is set to 0–1000 ppm.
Thermo Scientific 42iQHL Instruction Manual 3-87